Fiber optic system to measure adulteration in liquids using an RGB detection

O. X. Vera-Duarte, J. D Filoteo-Razo, J. M. Estudillo-Ayala, J. C. Hernandez-Garcia, D. Jauregui-Vazquez, J. M. Sierra-Hernandez, J. R. Martinez-Angulo, J. A. Martin-Vela, R. Rojas-Laguna


In this paper, we propose a fiber optic system to measure the changes in the RGB composition of light in liquid solutions using a plastic optical fiber (POF) as an intrinsic sensor. The measurement system is composed of a 3 W white light-emitting diode as the light source, a 20 cm long U-shaped POF, and an RGB photodiode array that allows us to detect the changes in the RGB composition of the light propagating through the POF. The U-shaped POF has a length of 5 mm without coating, which remains in contact with the liquid solutions. The tests were performed with different concentrations of a mixture of tequila and water. The results obtained with the RGB photodiode array showed that the system has a resolution of 0.39 % and a color change sensitivity of 0.1, 0.6, and 0.4 8–bits/% of sample for red, green, and blue colors, respectively. These results will allow us to design a low-cost prototype to measure the amount of adulteration in liquids.


Fiber optic; refractive index; sensor; RGB color

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